ovn-sbctl: eliminate a spurious test case error cause

ovn-sbctl: eliminate a spurious test case error cause

The "ovn-sbctl" test fails occasionally due to log messages
similar to these:

  jsonrpc|WARN|unix: receive error: Connection reset by peer
  reconnect|WARN|unix: connection dropped (Connection reset by peer)

Since we're already ignoring "Broken pipe" messages in this test
case, and the difference between EPIPE and ECONNRESET on send
is simply a matter of whether the peer had unconsumed data
in its receive buffer when the peer socket was closed, it should
be OK to ignore "reset by peer" logs as well.

This same type of failure has been observed in ovs-nbctl and
ovn-vtep-controller tests, so fix it there as well.

Signed-off-by: Lance Richardson <lrichard@redhat.com>
Acked-by: Ryan Moats <rmoats@us.ibm.com>
Signed-off-by: Russell Bryant <russell@ovn.org>